Recently, electronic devices have been required of saving of power consumption, and a demand for a semiconductor chip capable of efficiently converting power, namely a power semiconductor has been increasing. The power semiconductor is mainly used for power control of, for example, a hybrid vehicle and an electric vehicle and for home electric appliances such as an air conditioner that is large in power consumption. Particularly, the power semiconductor used in, for example, a hybrid vehicle and an electric vehicle is large in ampacity and large in amount of heat generation during use. Therefore, a cooling system high in heat dissipation has been required to prevent malfunction caused by a temperature rise. The heat generated in the power semiconductor is transferred to a heat sink via a heat spreader and cooled. Therefore, an adhesive composition that adheres the heat spreader to the heat sink has been required of high thermal conductivity.
Further, along with an increase in arithmetic processing capability of a semiconductor chip used in, for example, a personal computer and a mobile phone, an amount of heat generation is increasing, causing to be pointed out, for example, a problem that an arithmetic circuit of the semiconductor chip malfunctions due to a temperature rise and a problem that a portion where heat is accumulated is locally expanded and distorted to cause a rupture of a metal junction. Particularly, in a structure in which semiconductor chips are stacked, the heat generated from the semiconductor chips are likely to be accumulated in the semiconductor chips. Therefore, in order to efficiently dissipate the heat from the semiconductor chips, an adhesive composition that adheres a semiconductor chip to a wiring substrate or that adheres semiconductor chips to each other has been required of high thermal conductivity. Further, the adhesive composition is also required of excellent insulating properties as well as high thermal conductivity.
As a material used for the high thermal conductive adhesive composition, there is proposed an adhesive composition whose coefficient of thermal conductivity is increased by highly filling a thermosetting resin such as an epoxy resin with two types or more of high thermal conductive inorganic particles having different particle sizes, namely alumina particles (for example, see Patent Document 1). There is also proposed an adhesive composition including a polyimide resin whose thermal conductivity, insulating properties, and thermal resistance have been improved by adding inorganic particles high in heat dissipation (for example, see Patent Document 2). Further, there is proposed an adhesive composition whose heat dissipation is increased by adding to a resin high thermal conductive inorganic particles, namely aluminum nitride (for example, see Patent Document 3).